1. Technical Field
Photoresist cleaning solutions for rinsing semiconductor substrates before or after an exposing step during photoresist pattern formation are disclosed. More specifically, photoresist cleaning solutions are disclosed which comprise H2O and a nonionic surfactant compound as an additive. Methods for forming a photoresist pattern using the same are also disclosed.
2. Description of the Related Art
Conventional methods for forming photoresist patterns on a semiconductor substrate comprise forming an underlying layer on a semiconductor substrate, forming a photoresist film on the underlying layer, and then exposing the photoresist film to light and developing the exposed film to obtain a photoresist pattern on a part of the underlying layer to be exposed. When a positive-type photoresist film is used, the photoresist film of the exposed region is removed by a developing solution to form the photoresist pattern.
When a photoacid generator is irradiated by a light source, it generates acid. After exposure to the light source, main chains or branched chains of polymer matrix react with the generated acid and are decomposed or cross-linked, so that the polarity of the polymer matrix is considerably altered. This alteration in polarity of the polymer matrix results in solubility differences between the exposed and the unexposed portions of the polymer in the developing solution. As a result, the exposed portions that have reacted with the acid dissolve in the developing solution and are removed.
Meanwhile, acid is also generated from the photoresist film in the unexposed area by ghost images formed in undesired regions during exposing step. The amount of acid generated by the ghost images is relatively small compared to the acid generated in the exposed area. However, the protecting group of the polymer compound in the photoresist can be detached during the baking step by small amounts of acid, so that the unexposed photoresist is dissolved in the developing solution and an undesired pattern is formed in the unexposed area. Therefore, a solution to this problem of acid damage to the unexposed photoresist polymers is needed.